1. Field of the Invention
This invention relates to a new class of novel inorganic-organic hybrid thermosetting polymers that are formed from linear inorganic-organic hybrid polymers of varying molecular weight. These new high temperature oxidatively stable thermosetting polymers are formed from linear polymeric materials having repeat units that contain at least one alkynyl group for cross-linking purposes and at least one siloxanyl group. These novel thermosetting polymers can be further converted into ceramics at elevated temperatures.
2. Description of the Related Art
The cross linking of acetylenic polymers has been demonstrated by Neenan et al. in Hypercross-Lined Organic Solids: Preparation from Poly(aromatic diacetylenes) and Preliminary Measurement of Their Young's Modulus, Hardness, and Thermal Stability published in 21 MACROMOLECULES 3525-28 (1988), incorporated herein by reference. Other similar cross linking reactions are demonstrated by Callstrom et al. in Poly[ethynlyene(3-n-butyl-2,5-thiophenediyl)-ethynylene]: A Soluble Polymer Containing Diacetylene Units and Its Conversion to a Highly Cross-Linked Organic Solid published in 21 MACROMOLECULES 3528-30 (1988), incorporated herein by reference.
The recent literature reflects continuing major research efforts to advance fundamental knowledge in high temperature material design. See K. J. Wynne and R. W. Rice, Ceramics Via Polymer Pyrolysis 14 ANN. REV. MAT. SCI. 297 (1984), incorporated herein by reference in its entirety and for all purposes.
In the search for high temperature oxidatively stable materials considerable attention has been given to polymers containing inorganic elements within the polymer. See Table II of Maghsoodi et al. in Synthesis and Study of Silylene-Diacetylene Polymers published in 23 MACROMOLECULES pp. 4486 (1990), incorporated 11 herein by reference in its entirety and for all purposes.
A majority of the siloxane or silyl polymers show elastomeric properties rather than properties of more rigid polymeric products like thermosetting polymers or ceramics. Thus, in addition to thermal stability, there is also a need for polymers that behave more as thermosets and ceramics, upon further polymerization, and less like elastomeric polymers.
There is a need for oxidatively stable materials that have thermosetting properties for making rigid components therefrom, such as engine parts, turbine blades and matrices. These components must withstand high temperatures and be oxidatively stable and have sufficient strength to withstand the stress put on such components. Thus, there is a need for siloxane cross-linked thermosetting polymeric materials that show high temperature stability where weight percentage loss is limited to 50% or less when heated in excess of 600.degree. C. in an oxidative environment. In addition, there is a need for siloxane cross-linked thermosetting polymeric materials that behave more as rigid materials and less as elastomeric materials.